The invention relates to a compressed-air vane motor comprising a rotor which is mounted on antifriction bearings and has, distributed over the periphery, location slots in which vanes are guided in a radially displaceable manner and whose outer sealing edges bear by centrifugal force against the inner surface of a cylindrical outer shell To reduce wear and friction in this arrangement, the outer shell, displaced eccentrically relative to the rotor, is rotatably guided in the housing and is driven along by the friction between vanes and outer shell, and the cylindrical outer shell is rotatably mounted in the housing by at least one air bearing and to this end is accommodated with little radial clearance in an approximately circular-cylindrical guide bore of the housing.
The service life of such a compressed-air vane motor disclosed by German Offenlegungsschrift 2,621,486 is limited. A fairly reasonable service life can only be achieved if oil mist is added to the compressed air. For the drive of hand tools, however, the oil mist coming out of the hand tool is troublesome. In many areas, in particular in the foodstuffs industry, use of such compressed-air vane motors therefore has to be ruled out.
In the compressed-air vane motor disclosed by German Patent Specification 1,751,379, the outer shell is rotatably mounted via anti-friction bearings. Despite this efficient bearing arrangement and guidance, relatively heavy wear occurs between the outer shell and the vanes on account of deficient lubrication of the bearing so that, when operating with oil-free compressed air, the vane motor can only achieve a short service life.